Calculate your basal metabolic rate instantly using proven equations. Get accurate BMR estimates for weight management and fitness planning
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Basal Metabolic Rate (BMR) is the amount of energy expended while at rest in a neutrally temperate environment, and in a post-absorptive state (meaning that the digestive system is inactive, which requires about 12 hours of fasting). It represents the minimum amount of energy needed to keep your body functioning, including breathing, circulation, cell production, and brain function.
Understanding your BMR is crucial for effective weight management, fitness planning, and overall health optimization. It's the foundation upon which your Total Daily Energy Expenditure (TDEE) is calculated, helping you determine how many calories you need to consume to lose, maintain, or gain weight.
Our BMR calculator uses scientifically validated equations to estimate your basal metabolic rate. The most accurate method for most people is the Mifflin-St Jeor Equation, which was introduced in 1990 and has been shown to be more accurate than older formulas. We also provide the Harris-Benedict Equation and Katch-McArdle Formula for comparison.
Men: BMR = 10W + 6.25H - 5A + 5
Women: BMR = 10W + 6.25H - 5A - 161
W: Weight in kg, H: Height in cm, A: Age in years
Men: BMR = 13.397W + 4.799H - 5.677A + 88.362
Women: BMR = 9.247W + 3.098H - 4.330A + 447.593
Revised version from 1984, less accurate than Mifflin-St Jeor
BMR = 370 + 21.6 × (1 - F) × W
W: Weight in kg, F: Body fat percentage (decimal form)
Most accurate for lean individuals who know their body fat percentage
Several equations have been developed to estimate BMR. Each has different strengths and is more or less accurate depending on the population and available data:
Currently the most accurate equation for calculating BMR in adults. It's based on a large dataset and provides reliable estimates for most people.
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One of the oldest and most widely used equations. The 1984 revision improved accuracy but is still less precise than newer formulas.
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Uses lean body mass for calculation, making it more accurate for individuals who know their body fat percentage, especially athletes and lean individuals.
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BMR is influenced by numerous factors. Understanding these can help you optimize your metabolism and make better health decisions:
Decreases BMR
Metabolism slows down approximately 2-8% per decade after age 30 due to loss of muscle mass and hormonal changes
Men: Higher BMR
Men typically have higher BMR due to greater muscle mass and different hormonal profiles
Increases BMR
Muscle tissue burns more calories than fat tissue. Strength training can increase BMR by building muscle
Varies by fat vs muscle ratio
Individuals with higher muscle-to-fat ratios have higher BMR. Body fat percentage affects metabolic rate
Individual variation
Genetic factors can cause up to 26% variation in BMR between individuals with similar characteristics
Cold increases BMR
Cold environments force the body to burn more calories to maintain core temperature
Small meals increase BMR
Eating small, frequent meals can slightly increase BMR. Prolonged fasting may decrease BMR
Various effects
Thyroid function, stress hormones, and overall health status can significantly affect BMR
Modern Wisdom: A 2005 meta-analysis showed that even when controlling for all known factors, there's still a 26% unknown variance in BMR between people. This means calculations are estimates, and individual results may vary. Use BMR as a starting point and adjust based on actual results.
Get precise calorie targets for weight loss, maintenance, or muscle gain based on your metabolic rate
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Calculate your basal metabolic rate instantly using proven equations. Get accurate BMR estimates for weight management and fitness planning
BMR (Basal Metabolic Rate) is the number of calories your body burns at rest to maintain basic physiological functions like breathing, circulation, and organ function. It's calculated using equations like Mifflin-St Jeor: For men BMR = 10W + 6.25H - 5A + 5, for women BMR = 10W + 6.25H - 5A - 161, where W is weight in kg, H is height in cm, and A is age in years.
BMR is the calories burned at complete rest in a fasting state, while TDEE (Total Daily Energy Expenditure) is BMR multiplied by an activity factor. TDEE represents all calories burned in a day including exercise, daily activities, and digestion.
The Mifflin-St Jeor equation is generally the most accurate for most people and is recommended. Use Katch-McArdle if you know your body fat percentage and are relatively lean (it requires lean body mass). The Harris-Benedict equation is an older formula that's less accurate but still widely used.
To lose weight, consume fewer calories than your TDEE. For safe weight loss, aim for 500 calories less than your TDEE per day, which typically results in 0.5kg (1lb) loss per week. Never go below 1200 calories for women or 1500 for men without medical supervision.
BMR is affected by age (decreases with age), gender (men have higher BMR), muscle mass (more muscle = higher BMR), genetics, body composition, hormones, and environmental temperature. Regular strength training can increase BMR by building muscle.
BMR and RMR (Resting Metabolic Rate) are often used interchangeably. Technically, BMR is measured under very strict conditions (complete rest, fasting, neutral temperature), while RMR can be measured in a more relaxed state. In practice, they're very similar for most calculations.
BMR calculators provide estimates with 10-15% accuracy for most people. Individual variations due to genetics, muscle mass, hormones, and other factors can affect results. Use BMR as a starting point and adjust based on your actual weight changes over 2-4 weeks.
Aerobic exercise like running or cycling doesn't directly increase BMR, but anaerobic exercise like weight lifting builds muscle mass, which increases BMR. The more muscle you have, the more calories you burn at rest. This is why strength training is important for long-term metabolism.
The most accurate way is through indirect calorimetry in a clinical setting. Handheld metabolic devices provide good estimates. Online calculators using proven equations are convenient but should be validated with actual results over time.
Yes, our BMR calculator is completely free to use with no registration, payment, or hidden fees. You can calculate your basal metabolic rate as many times as you want, try different equations, and use it for personal health and fitness planning.
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